Poly-v Vs. V Belts Vs. Link Belts For Vibration

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mattthemuppet2

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Hi all,

studiously avoiding work here, so the mind turns to that other existential question (2nd to "when's dessert"):

which is less likely to suffer from belt induced vibrations - poly-V, V or link belts? Are poly-V belts prone to the kind of QC issues that can affect V belts?

It's not an entirely idle Q as I've been chasing vibration on my Atlas 618 for a while and I'm just about (hah, just!) to replace the treadmill motor -> countershaft 1/2in link belt with a poly-V belt, which will leave the countershaft -> spindle with a 3/8in link belt. That belt suffers from a degree of slip unless the belt tension is really high. So, one thought that I've been entertaining instead of working is to replace the spindle and countershaft pulleys with poly-V belt pulleys.

ta very much!
 
Due to the age of the lathe, I wonder if the v-belt is too far down into the pulley, since you have to have lots of tension to reduce slippage. Does the bottom of the pulley groove appear shiny as if the belt is running on that instead of the sides? I do know that a link belt will remove most vibrations that are induced by the motor and countershaft if used in both positions. A multi rib poly belt is also effective in reducing the same vibrations but not to the same extent.
 
The poly-V has a lot less mass so should be less prone to causing vibrations. The twin belts on my table saw blew up on a weekend so I tired some link belt I had. The saw ran much quieter with them and seamed smoother but it probably weights 5 or 600 pounds so that my have been in my head. BUT I couldn't get them tight enough to not slip under load, so replaced them with v-belts again when the stores opened. I used link belts on my shaper but it probably weighs 4000 pounds so vibration isn't an issue. I ran a poly-V off a treadmill motor to the spindle on a tool grinder I built and it runs smooth as glass.
Can't give any definitive answers but there's a couple of results to ponder.

Greg
 
I run poly-vee belt on my 9" SBL. Dad grooved the cone pulleys to accept the J-section belt. Runs nice. Worked for over 50 years now!
Also have a poly vee belt/ pulley setup on my B & S surface grinder that replaced a flat belt that someone else put on there to replace the original O-ring belt drive.
If you have room for it, put it on there. Just remember, it's like a flat belt drive, alignment is critical. Not like a vee belt drive where you can get away with some mis-alignment.
 
pdentrem said:
Due to the age of the lathe, I wonder if the v-belt is too far down into the pulley, since you have to have lots of tension to reduce slippage. Does the bottom of the pulley groove appear shiny as if the belt is running on that instead of the sides? I do know that a link belt will remove most vibrations that are induced by the motor and countershaft if used in both positions. A multi rib poly belt is also effective in reducing the same vibrations but not to the same extent.
Click to expand...

good idea, but if anything the 3/8 V-belt and link belts ride a little too high in the pulley. I wonder if oil flung off the backgear teeth is contaminating the belt, looks a little black on the sides? To be honest the pulleys are pretty small diameter (1 and 2 1/2-3in at the bottom of the V) which probably doesn't help - something the poly-V should be better at.

f350ca said:
The poly-V has a lot less mass so should be less prone to causing vibrations. The twin belts on my table saw blew up on a weekend so I tired some link belt I had. The saw ran much quieter with them and seamed smoother but it probably weights 5 or 600 pounds so that my have been in my head. BUT I couldn't get them tight enough to not slip under load, so replaced them with v-belts again when the stores opened. I used link belts on my shaper but it probably weighs 4000 pounds so vibration isn't an issue. I ran a poly-V off a treadmill motor to the spindle on a tool grinder I built and it runs smooth as glass.
Can't give any definitive answers but there's a couple of results to ponder.

Greg
Click to expand...

thanks for the input Greg, plenty to think about there. Certainly adding the poly-V belt to the motor should give me another point of reference too. With a machine this old, worn and cludged together I sometimes feel like I'm chasing my tail.
 
mattthemuppet said:
1 and 2 1/2-3in at the bottom of the V)
Click to expand...
So the smaller one is about 2" od.? That's pushing it pretty hard for a 1/2" v belt. If you don't go with the ribbed belt I'd recommend a 3/8" cogged v belt (replace the pulleys, of course). Cogged belts work much better with small pulleys and are are less likely to take a set (a common cause of vibration with v belts but not likely with link belts).
 
2" sounds about right, perhaps a bit smaller though it's with a 3/8" link belt. The one on the motor pulley was about that size with a 1/2" belt and that really was pushing it. That's a big part of the reason for putting the original flywheel back on the motor too.

thanks for the input Ken! There would be room on the spindle pulley for at least 2 different sized poly-V pulleys which should give me a decent speed range with the treadmill motor and the back gears. It'll be some way off as a project because of all the others in the way AND I'd have to learn how to cut gears for the bit that meshes with the back gear. Might be able to buy something suitable and press it on though..
 
I try to always remove tension on idle belts and saw blades of all types. I have not run link belt on any thing yet. To many belts to change out. I did replace both belts on my 10f yesterday and wow. Just used plain v belts. First time spinning it up for test run and the lathe bolted to about 400 lb bench was going to dance across the shop floor with over 100 lb on bench shelves. So much nicer now. I still need to replace motor pulleythat I have. Belt was riding in bottom of v. I wiped off any excess greesy residue off gears and pulleys.
Jack

Sent from my SGH-I337M using Tapatalk
 
I've managed to get the vibration down alot and I'm hoping most of the rest will go away once I put the flywheel back on the treadmill motor. Lots of mass, already balanced and a hopefully true countershaft pulley once I've finished with it (screwed up the first attempt).

I have to say though, given the amount of time I've spent fixing up bodges and badly fixed bits on this lathe, the idea of a new lathe has a lot of appeal!
 
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